Mobile devices such as, but not limited to, mobile phones, smart phones, personal digital assistants (PDAs), tablets, laptops or other electronic devices, etc., increasingly include voice recognition systems to provide hands free voice control of the devices. Although voice recognition technologies have been improving, accurate voice recognition remains a technical challenge when the voice of interest is in the presence of other talkers or ambient noise. These technical challenges exist not only for voice recognition technologies, but also for voice processing such as that used in telephony which today may be performed using almost any electronic device having a suitable telephony application, notwithstanding the prevalence of mobile phones and smart phones.
A particular challenge when implementing voice transmission or voice recognition systems on mobile devices is that many types of mobile devices support use cases where the user (and therefore the user's voice) may be at different positions relative to the mobile device depending on the use case. Adding to the challenge is that various noise sources including other talkers (i.e. jammer voices) may also be located at different positions relative to the mobile device. Some of these noise sources may vary as a function of time in terms of location and magnitude. All of these factors make up the acoustic environment in which a mobile device operates and impacts the sound picked up by the mobile device microphones. Also, as the mobile device is moved or is positioned in certain ways, the acoustic environment of the mobile device also changes accordingly thereby also changing the sound picked up by the mobile device's microphones. Voice sound that may be recognized by the voice recognition system or by a listener on the receiving side of a voice transmission system under one acoustic environment may be unrecognizable under certain changed conditions due to mobile device motion, positioning, or ambient noise levels. Various other conditions in the surrounding environment can add noise, echo or cause other acoustically undesirable conditions that also adversely impact the voice recognition system or voice transmission system.
More specifically, the mobile device acoustic environment impacts the operation of signal processing components such as microphone arrays, noise suppressors, echo cancellation systems and signal conditioning that is used to improve both voice recognition and voice call performance. For mobile devices and also for stationary devices, the speaker and other jammer speakers or other noise sources may also change locations with respect to the device microphones. This also results in undesirable impacts on the acoustic environment and may result in voice being unrecognizable by the voice recognition system or a listener due to noise interference caused by the jammer speakers or other noise sources.